FIG. 1 is a cross sectional view of a conventional solid state image pickup device. Photosensitive elements (photodiodes) 2, 2, . . . of the image pickup device are formed by diffusing N-type impurities on the surface of a P-type silicon substrate 1. The surface of the substrate 1 is covered with an insulating protective film 3 such as a PSG film, plasma SiN film, or the like. Light shielding films 4, 4, . . . made of Al (aluminum) are formed in the protective film 3 above the regions between photodiodes 2 and 2. The protective film 3 is further covered with another protective film 5. There are formed in the protective film 3 color layers including Ye (yellow) layers 6, Cy (cyan) layers 7, and Mg (magenta) layers 8. These color layers are formed in the following manner. First, a protective film 5a is formed on the protective film 3. Water soluble transparent resist (e.g. FCR500, a product name of Fuji Yakuhin Kabushiki Kaisha) is coated on the surface of the protective film 5a. The resist film is then etched while leaving a pattern (6), by using an etching liquid made of gelatin or casein with 1 weight % ammonium dichromate being added. The remaining pattern (6) is dyed with an Ye acid dyeing liquid, to form the Ye layers 6. Thereafter, a protective film 5b is formed and water soluble transparent resist is coated on the surface of the protective film 5b. The resist layer is etched while leaving a pattern (7) in a similar manner as above. The remaining pattern (7) is dyed with a Cy acid dyeing liquid to form the Cy layers 7. Thereafter, a protective film 5c is formed and water soluble transparent resist is coated on the surface of the protective film 5c. The resist layer is etched while leaving a pattern (8) in the similar manner as above. The remaining pattern (8) is dyed with an Mg acid dyeing liquid to form the Mg layers 8. Thereafter, a smoothing layer 5d is formed using oil soluble transparent resist. In the above manner, three color layers 7 to 9 are formed above the photodiodes 2, 2, . . .
Micro lenses 10, 10, . . . are formed on the smoothing layer 5d at the positions just above the photodiodes 2, 2, . . . . The lenses are formed by using any one of various known methods.
If micro lenses 10, 10, . . . are formed using a conventional method, spaces are essentially formed between the lenses 10, 10, . . . In other words, there exist non-lens regions 11, 11, . . . Light beams incident to the non-lens regions become stray light beams and cause the smear phenomenon to be described later. Light beams incident to the non-lens region are not efficiently used as image pickup signals, thereby lowering an aperture efficiency. It is therefore inevitable that the sensitivity of the image pickup device is degraded. Moreover, the light beams obliquely incident to the micro lens 10 become stray light beam similarly to those light beams incident to the non-lens regions 11, thereby causing the smear phenomenon and degrading the sensitivity.